Esophageal Cancer Test Identifies Patients Resistance to Chemoradiation Therapy

A multi-biomarker test accurately predicts the response to presurgical chemoradiation therapy (CTRT) in patients with esophageal adenocarcinoma (EC).

The two main types of esophageal cancer are adenocarcinoma and squamous cell carcinoma, and the most common form of the disease in the USA is adenocarcinoma which is most prevalent in Caucasian men between the ages of 50 and 70.

The biomarker test analyzes the localization of three protein biomarkers, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), glioblastoma zinc finger 1 (Gli1) and sonic hedgehog (SHH), to classify tumors as either responsive to, or resistant to, CTRT. The first validation study was performed at a single center using 167 samples from patients that had been treated with a CTRT regimen. The test was performed on formalin-fixed paraffin embedded (FFPE) EC tissue.

The DecisionDx-EC test (Castle Biosciences; Friendswood, TX, USA) showed a specificity of 97% and positive (PPV) and negative (NPV) predictive values reaching 82% and 94%, respectively. In a second, multicenter validation study, results were similar. Of 65 patient cases, 68% of whom had been treated with the same regimen, the study reported 95% specificity with a PPV and NPV of 83% and 77%, respectively.

The scientists also studied a new test for rectal adenocarcinoma (RC) that uses the same biomarkers as the EC test to predict resistance to preoperative CTRT. The study looked at FFPE samples from 10 patients with locoregional RC and showed an accuracy of 80%, with specificity and PPV values of 100%. These results suggest that the assay was able to identify 100% of those patients who would respond favorably to CTRT. Expanded validation of the biomarker panel for RC is currently underway.

Sunil S. Badve, MD, FRCPath, a professor of Pathology and Laboratory Medicine at Indiana University (Indianapolis, IN, USA) and coauthor of the study said, “The ability to identify resistance to standard of care therapies could allow for selection of more appropriate treatment strategies and improved patient outcomes.” The study was presented at the Digestive Disease Week (DDW) Annual Meeting held May 3–6, 2014, in Chicago (IL, USA).

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Castle Biosciences
Indiana University